The biggest hints are probably in the episode where Nadie ignores Ellis much of the time to socialize with Ricardo, and everybody assumes that they're a couple and that Ellis is Ricardo's child from a previous marriage. Ellis spends her time seething in jealousy, and when Nadie tells that they should take a shower before dinner, Ellis simply throws off all her clothes, leading to Nadie's flustered "not together!"

In the same episode, Ellis also asks Nadie if they could be considered a married couple. Ho-hum.